“Princeton economist, Alan B. Krueger, took the offer, and after two years recently concluded that Professor Peterson had it all wrong — that not even the black students using vouchers had made any test gains. And Mr. Myers, Professor Peterson’s former research partner, agrees, calling Professor Krueger’s work “a fine interpretation of the results.”What makes this a cautionary tale for political leaders seeking to draft public policy from supposedly scientific research is the mundane nature of the apparent miscalculations. Professor Krueger concluded that the original study had failed to count 292 black students whose test scores should have been included. And once they are added — making the sample larger and statistically more reliable — vouchers appear to have made no difference for any group.”